The structure according to the present invention finds special application in the packaging of goods of small dimensions within a flexible walled receptacle which generally, in turn, is disposed within a conventional shipping container. Examples of such goods are granular or powdered material, small fruits, such as cherries packed in syrups, or the like. Such goods are generally placed within the flexible walled container at ambient pressure, and it is desirable to reduce the ambient pressure on the packaged material by placing the shipping container with the flexible walled receptacle therein within a vacuum chamber, the latter being provided with means for sealing the open top of the flexible walled container, generally by heat sealing means, the flexible walled receptacle being generally made with film material compatible with heat sealing operations.
Such loaded containers are quite heavy, and the loading of the container and the flexible walled receptacle therein within the vacuum chamber does not lend itself readily to handling by an operator.
According to the invention it is possible to arrange a plurality of vacuum chambers in tandem fashion, so that the loading into one chamber can be accomplished while another chamber is having the sealing operation carried on therein, still another chamber being unloaded after the sealing operation. The apparatus is characterized by conveyor means having conveyor sections always in alignment for movement of the shipping container to loading and unloading position, each of the chambers being characterized by a movable wall having conveyor sections mounted on the inside and outside thereof, so that at all times there is a conveyor section in alignment with the main conveyor means moving the loaded containers to position for treatment within a vacuum chamber or removal therefrom.
The apparatus is also characterized by the movable wall having elements of heat sealing means carried thereon, so that when the container is moved into position for sealing, a movable sealing bar can more cooperatively with the sealing bar carried by the movable wall to seal the flexible wall container.